For the last fifteen years, concerns about the potential explosion hazards inherent in connecting transportation vessels (marine, truck, rail cars, etc.) and fixed storage facilities have delayed the establishment of regulations limiting hydrocarbon emissions during hydrocarbon transfer operations. However, the Clean Air Act Amendment of 1990 and local regulators are requiring early installation dates for vapor control systems in several jurisdictions. The U.S. Coast Guard is adopting new regulations for the safe design, installation, and operations of marine vapor control systems. These regulations have been promulgated in the belief that the result will be fewer vessels and facilities damaged from fire and explosion, overfilling, and over or under pressurization; fewer injuries and deaths from fire and explosions; and less oil spilled. There continues to be considerable controversy as to the effectiveness of existing detonation flame arresters in these applications. Heretofore, detonation arresters of the crimp ribbon spiral wound type have thus far been subject to test protocol set out by the U.S. Coast Guard (1990). A quick closing flame barrier valve and suppressant has also been tested to investigate the feasibility of an open pipe alternative for detonation arresters. According to the Federal Register, Vol. 55 No. 120, Jun. 21, 1990, the U.S. Coast Guard published test protocol for devices to accomplish the above. Recent tests conducted by industry suggest that there is no such thing as an "all purpose" arrester that works under all possible conditions actually attainable in marine vapor recovery systems. The main obstacle has been an inability to stop the impulse momentum of the detonation or deflagration. It has been demonstrated that automatic shutdown devices cannot react fast enough to isolate the system once a detonation wave has developed. While blowout disks are not prohibited, these alone are not adequate since the flame front will continue despite elimination of the pressure wave.
Based on information conveyed by researchers, it is the consensus of those who have observed numerous tests that the above mentioned devices do not reliably work in this application. Although some success has been achieved in arresting detonation shock waves, mechanical failure of this equipment has persisted. This has led to promulgation of regulations requiring three-phase protection for marine vapor recovery systems to reduce the probability of fire and explosions being conveyed between ship and shore. This three-phase protection includes: 1) controlling the vapor mixture outside of its flammable range; 2) engineering controls to eliminate sources of ignition; and, 3) mechanical detonation arresters. If a reliable detonation arrester can be developed, the all encompassing nature of these regulations might be relaxed, saving industry considerable operating cost and improving operating safety.